The Polycrystalline-Si Contact to GaAs

Polycrystalline-Si/GaAs interfaces have been prepared by depositing hydrogenated amorphous Si (a-Si) onto GaAs in a silane plasma at 450°C and annealing at temperatures between 600° and 1050°C. Rutherford backscattering, secondary ion mass spectroscopy, and transmission electron microscopy analyses show that the resulting polycrystalline-Si/GaAs interface is metallurgically stable when the Si is undoped, while significant interdiffusion occurs when P or As are added to the Si. The Si diffusion into the GaAs is rapid (D = 10 -11 cm2/s at 1000°C) depends on concentration and increases with increasing P content in the Si. Ohmic contacts prepared using Si(P-4 atom percent (aio))/GaAs (semi-insulating) annealed at 800° and 1050°C, gave contact resistance of 1.7 × 100-4 and 1.2 × 10 -4 Ω cm2, respectively. © 1986, The Electrochemical Society, Inc. All rights reserved.